Circuit interrupters are electrical components that are used to open an electrical circuit, interrupting the flow of current. One example of a circuit interrupter is a switch, which typically includes two electrical contacts in one either a closed state or an open state thereby opening or closing an electrical circuit.
Another example of a circuit interrupter is a circuit breaker. A circuit breaker may be used, for example, in an electrical panel to limit the amount of current allowed to flow through attached electrical wiring. A circuit breaker is designed to protect an electrical circuit from damage caused by various dangerous fault situations that may develop in an electrical circuit including but not limited to, an overload, a ground fault or a short circuit. If a fault condition, such as, a power surge occurs in the electrical circuit, the breaker will trip open thereby interrupting the supply of electrical power to the circuit. Circuit breakers are generally provided to protect the electrical wiring by limiting the amount of current transmitted through the wires to a level that will not damage them. Circuit breakers can also prevent destruction of the devices that may draw too much current. Some common types of circuit interrupters include: thermal magnetic circuit breakers, inverse time circuit breakers and instantaneous-trip circuit breakers.
Most circuit breakers have a “line” terminal connectable to an electrical power source, such as, a power line electrically connected to the secondary of a power company transformer. Additionally, most circuit breakers further include a “load” terminal electrically connectable to the circuit (i.e., the wiring) that the circuit breaker is intended to protect.
Typically, a single pole circuit interrupter has two contacts positioned inside of a housing or enclosure. The first contact is stationary and may be connected to either the line or the load. The second contact is movable with respect to the first contact, such that, when the circuit breaker is in the “off” or tripped position, a physical gap exists between the first and second contact.
A problem with the above-described circuit interrupters arises when energized contacts are transitioned from a closed state (in which current is flowing across the contacts) to an opened state (in which current is interrupted from flowing) while under load. As the contacts separate transitioning from a closed to an open state, or when the opposite occurs, when the contacts transition from an opened state to a closed state, an electric arc may form in the gap (the physical space) between the contacts as the contacts are drawn apart.
The development of an arc during switching or tripping of the circuit interrupter negatively affects the overall operation of the circuit interrupter, even potentially creating safety hazards.
These negative effects can have adverse consequences on the operation of the circuit interrupter. One possible consequence is that the arc may short to other objects in the circuit interrupter and/or to surrounding objects, causing damage and presenting a potential fire or safety hazard.
Another consequence of arcing is that the arc energy damages the contacts, causing some material to escape into the air as fine particulate matter. The debris which has been melted off of the contacts can migrate or be flung into the mechanism of the circuit interrupter, destroying the mechanism or reducing its operational lifespan.
Another effect of arcing stems from the extremely high temperature of the arc (tens of thousands of degrees Celsius), which can impact the surrounding gas molecules creating ozone, carbon monoxide, and other dangerous compounds. The arc can also ionize surrounding gasses, potentially creating alternate conduction paths.
Because of these detrimental effects it is very important to quickly cool and quench the arc to prevent damage to the circuit interrupter and the above-described dangerous situations.
Various techniques for improved arc quenching are known. For example, U.S. Published Patent Applications No. 2012/0037598 and 2012/0261382, assigned to Carling Technologies, Inc., variously relate to the use of an electromagnetic field to guide an arc toward an arc splitter.
However, generating an electromagnetic field to move an arc typically requires the use of electrical power, which in turn, will generate heat in the device. This is undesirable from the standpoint that the excessive heat will need to be dispersed; but additionally, this requires utilization of additional power, thereby making the system less energy efficient.
It is therefore desired to provide arc quenching usable with a circuit interrupter that overcomes the above-described limitations.